Water filters are generally divided into two classes: point of entry water filters and point of use water filters. Point of use water filters can be installed at a kitchen sink or within a refrigerator appliance in order to filter water entering such devices. In particular, water filters are generally provided with a filtering media such as a block of activated carbon. The water filter's filtering media can adsorb or remove contaminants such as chlorine and lead from water prior to delivering such water to a user. For example, the water filter can filter water prior to such water entering the refrigerator's ice maker or water dispenser.
The block of activated carbon has pores that permit a flow of water through the block. By passing through the pores, contaminants such as sand, rust, and cysts within the flow of water can be mechanically filtered out of the water. Similarly, volatile organic compounds such as chloroform, lindane, and atrazine can be adsorbed into pore surfaces as water moves through the carbon block. However, at some point, the pore surfaces become saturated with contaminates and can no longer adsorb the incoming contaminates in the water stream. In contrast to mechanically filtered contaminants that clog the pores over time, the adsorbed contaminants generally do not impede flow through the filter and therefore there is no consumer queue alerting them that the filter is no longer properly functioning.
In addition, the pores are generally too large to prevent microbial contaminants such as bacteria from passing through the block. Similarly, the adsorption characteristics of activated carbon are inconsistent with removing bacteria from the flow of water. Conditions within the filtering media can also provide for large scale bacteria growth, particularly over time. For example, bacteria can start to grow within the carbon block given the right water conditions and sufficient time.
To hinder such bacteria growth, the water filter is preferably replaced or serviced about every six months regardless of its current performance. However, many consumers forget to replace the water filter or choose to simply ignore the recommendation. In particular, certain consumers only replace the water filter after it has become blocked, e.g., by sediment accumulation around and within the carbon block.
Accordingly, a water filter with features for blocking or impeding a flow of water through the water filter in order to encourage replacement of the water filter would be useful. In particular, a water filter with features for blocking or impeding a flow of water through the water filter after about six months in order to encourage replacement of the water filter would be useful.